Control mechanism for air conditioning apparatus



y 1961 J. N. GILLHAM EIAL 2,986,016

CONTROL MECHANISM FOR AIR CONDITIONING APPARATUS Filed Sept. 16, 1957 4 Sheets-Sheet 1 c INVENTORS JOHN N. GILLHAM FIG .5 JAMES R. DQISIGNORE ATTORNEY May '30, 1961 J. N. GILLHAM ETAL 2,936,016

CONTROL MECHANISM FOR AIR CONDITIONING APPARATUS Filed Sept. 16, 1957 4 Sheets-Sheet 2 INVENTOR.

JOHN N- GILLHAM BY JAMES R. DGISIGNORE ATTOR NEY May 30, 1961 J. N. GILLHAM ETA].

CONTROL MECHANISM FOR AIR CONDITIONING APPARATUS Filed Sept. 16, 1957 4 Sheets-Sheet 3 JOHN N.GlLLHAM By JAMES R. DGISIGNORE ATTORNEY y 1961 J. N. GILLHAM EIAL 2,986,016

CONTROL MECHANISM FOR AIR CONDITIONING APPARATUS Filed Sept. 16, 1957 4 Sheets-Sheet 4 IOI FIGS

FIG.9

INVENTORS JOHN N-GILLHAM y JAMES R. DC'SIGNORE ATTORNEY FIGJO United States Patent Qffiice CONTROL MECHANISM FOR AIR CONDITIONING APPARATUS John N. Gillham, Louisville, Ky., and James R. Qel Slgnore, North Syracuse, N.Y., asslgnors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Sept. 16, 1957, Ser. No. 684,044 Claims. ((162-161 This invention relates generally to air conditioning apparatus. More particularly, this invention relates to control mechanism for operating air conditioning equipment. Air conditioning units of the kind under consideration are employed to cool and/or dehumidify air in an area such as a roomor the like. In addition thereto the units are also employed to supply ventilation air to the 'room by delivering outdoor air thereto and to exhaust em from the room to the outside. If desired the air within the room may be circulated therein through a filter located in the unit.

These units include a refrigeration system, located within a casing mounted in a room comprising an evaporator arranged in heat transfer relation with air in the room moving under the influence of a fan in the unit, and a condenser arranged in heat transfer relation with air outside the room being served by the unit. A second fan controls the flow of air over the condenser. A partition, disposed in the casing, separates the evaporator and the condenser sections. Dampers in the partition operate in conjunction with the fans to effect the ventilation and air exhaustion mentioned above.

When the unit is operated to cool air within the room being served, a thermostat arranged to sense the temperature of air being drawn into the unit by the evaporator fan preparatory to being delivered over the evaporator controls the operation of the compressor in the refrigeration system. As the unit cycles off, the fans continue to operate to provide air circulation within the room. However, a rehumidification effect occurs as moisture, formed on the surface of the evaporator when the unit was operating to cool the air, is evaporated in the air stream flowing over the evaporator coil. It will be appreciated that during operation of the compressor the air routed over the evaporator will have its temperature reduced below its dew point causing moisture from the air to collect on the surface of the evaporator. Thus the air within the room is dehumidified as the latent heat as well as sensible heat is extracted from that portion continuously flowing over the coil.

The chief object of this invention involves the provision of a control mechanism for an air conditioning unit that will substantially reduce the rehumidification efiect produced by conventional units when the refrigeration system cycles off and the air circulating fans continue operation.

Another object of this invention is the provision of an improved mechanical linkage for operating the dampers for regulating the supply of ventilation air to and the exhaustion of air from an area served by the unit.

A further object is the provision of an improved control mechanism for use with an air conditioning unit wherein a linkage controlling operation of the dampers in the unit is also associated with the means in the control scheme for reducing rehumidification effects of the kind described.

These and other objects of the invention are attained by the provision of a control means for an air conditioning unit that includes means for regulating the passage of 2 air over the evaporator in response to the temperature of the air in the room being served by the unit, means for regulating operation of each damper and means operative in response to the operation of the damper control means for actuating the air passage regulating means.

Other objects and advantages of the invention will be apparent from a consideration of the ensuing specification and drawings in which:

Figure l is a perspective view, partially cut awayto better show the components thereof, of a unit air conditioner embodying the present invention; showing the damper doors in a closed position to permit recirculation of the air to and from the conditioned area over the evaporator or cooling element of the unit; and

Figure 2 is an elevational detail view of the partition wall, with the damper doors arranged to permit exhaustion of air from the conditioned area; and

Figure 3 is a view similar to Figure 2, with the damper doors shown arranged for admitting fresh air to the conditioned area for ventilation purposes; and

Figure 4 is a perspective detail view of the switch mounting brace with the control knobs and switches thereon; and

Figure 5 is a circuit diagram of the electrical circuit employed; and

Figure 6 is a detail view of the novel manual control knobs; and

Figure 7 is a front view of a thermostatic switch unit used in the invention; and

Figure 8 is a side view with parts broken away for clarity, of the unit shown in Figure 7; and

Figure 9 is a view similar to Figure 7 showing certain of the parts of the unit in a different operating position; and

Figure 10 is a view similar to Figure 8 showing certain of the parts of the unit in a different operating position; and

Figure 11 is a fragmentary view of the fan switch and operating cam used in the invention.

Referring now more particularly to the drawings, like numerals in the various figures will be taken to designate like parts.

As best seen in Figure 1, an air conditioning unit 10 is provided, in which all of the components are encased in a housing 11. The front of the housing (as viewed to the left of Figure l), is provided with a facade grill 12, having louvres 13 and 14 arranged therein. Louvres 13 are at a steeper angle than louvres 14, and the facade grill is reversible, whereby either louvres 13 or louvres 14 will assume an uppermost position to provide for different types of air stream deflection. As viewed in the drawing, the grill is arranged with louvres 13 functioning to admit air to the unit, and louvres 14 functioning as an outlet.

Within housing 11, a refrigeration system is provided. The refrigeration system comprises: an evaporator coil or cooling element 15, a compressor 16, a condenser 17, and expansion member (not shown), with .all of said elements in a closed fluid circuit, through which a re frigerant fiows. Compressor 16 is sealed unit including a driving motor for the compressor. A partition wall 20 extends across the unit to separate the cooling element 15 of the refrigeration system from the other components of said system. Cooling element 15 extends across the entire unit and from top to bottom thereof. The portion of the unit containing the cooling element is arranged in communication with the conditioned area, and the portion of the unit to the right of partition wall 20, as viewed in Figure 1, is arranged in communication with the ambient atmosphere. Plenum deck 23 divides the portion of the unit containing the cooling element 15 into an intake plenum 21 and a discharge plenum 22. Wing portion 23' supports deck 23 on partition 20. Filter 24 is mounted over evaporator coil 15, to filter the air admitted through intake louvres 13 to intake plenum 21. Plenum deck 23 is provided with an aperture 28, beneath which centrifugal fan 29 is arranged. Scroll 30 supported on plenum deck 23 partially encases fan 29. Apertures 31 in each side wall of scroll 30 admit air from the intake plenum 21 to fan 29, whence thehair stream is centrifugally directed to exhaust plenum 2 above plenum deck 23.

A condenser fan 35 is arranged adjacent the coils of condenser 17, to direct an air stream thereacross. Twospeed fan motor 36 is coupled to fan 29 and fan 35, to drive same. It will of course be apparent to those skilled in the art that separate motors may be provided for the condenser fan 35 and the evaporator fan 29.

The passage of the air stream from the conditioned area through the unit is produced primarily by evaporator fan 29. The air paths through which the air stream may fiow are, however, determined by dampers 40 and 41 in partition wall 20. Ventilating damper 41 is supported at the lower end of damper shaft 42, which extends upward through plenum deck 23. Exhaust damper 40 is freely supported on shaft 42 at the upper end thereof, in exhaust plenum 22. The opening or closing of these dampers determines whether or not there may be an interchange of air between the conditioned area and the ambient, as will become hereinafter more apparent.

The positioning of the dampers 40 and 41 in conjunction with partition wall 20 is most clearly seen in Figures 2 and 3. As seen in Figure 2, exhaust damper 40 is shown in the open position to permit flow of air to the ambient from the conditioned area through partition wall 20. A screen 45 is provided in exhaust aperture 46 formed in the upper part of partition Wall 20, and over which the damper 40 is mounted. Damper shaft 42 is supported by U-shaped exhaust damper bracket 47, and ventilating damper bracket 48. The body portions of the damper brackets as viewed in the drawings, are secured to partition wall 20, and the arm portions of the brackets extend out to support the damper shaft. Exhaust damper biasing spring 49 is positioned about damper shaft 42, with one leg of the spring 49 engaging bracket 47, and the other leg of the spring engaging damper 40, whereby the damper will normally be biased to a closed position. Ventilating damper door 41, shown in the closed position in Figure 2, is best seen in Figure 3 in open position, where it is mounted over ventilating port 51 in partition wall 20, said port 51 provided with screen 52. A biasing spring 53, similar to spring 49, is mounted about damper shaft 42 between the arms of U-shaperl ventilating damper bracket 48, and the legs of the spring bear respectively against the bracket 48 and the damper 41, to bias the damper to closed position.

Dampers 40 and 41 each have mounting arms, permitting securement of the damper to the damper shaft. The upper mounting arm 40' of exhaust damper 40, as seen in Figure 3, is provided with two upstanding lugs 55 diametrically opposed about shaft 42. Pin 56 extends through shaft 42 and serves to limit the motions of damper door 40 through a desired angle of rotation, and to permit rotation of shaft 42 through a desired angle, without affecting the position of damper 40. Pin 56 further.supports damper shaft 42 in assembled position.

Lower ventilating damper mounting arm 41 is similarly provided with upstanding lugs 57, diametrically positioned about shaft 42. Pin 58 extends through shaft 42 and bears against lugs 57 to provide a lost motion connection between shaft 42 and damper 41 through 180.

Fan motor shaft slot 60 is formed, as seen to the right in Figure 2, facilitates removal of the fan and fan motor for repair or maintenance.

it will be appreciated that each of the damper doors is provided with appropriate insulation about its edges, so as to assure substantially airtight closure of the openings in the partition wall 20, when the dampers are closed. Opening and closing of the dampers is accomplished by means of control linkage 65, as best seen in Figure 4. Control linkage is secured to crank arm 61, formed at the lower end of damper shaft 42.

The position of the dampers is manually accomplished by means of ventilating control knob 70, best seen in Figures 4 and 6. Ventilating knob 70 in the shape of a ratchet wheel, having a plurality of indicating flag fingers 71, is arranged at the front of the unit, or some other readily accessible portion thereof, so that one of said fingers 71 is prominently exposed to indicate the condition of operation of the unit, or in this case, more particularly the degree of ventilation or exhaust for which the damper doors are set. The fiag fingers 71 are marked with indicia, as seen in Figure 6, which will be hereinafter more fully explained. Knob 70 is secured to rotate with shaft 73, which is journalled in mounting brace 75, extending across the front of the unit, as seen in Figure l. Shaft 73 is provided with a cam surface fiat 76, which engages switch arm 77 of damper-fan microswitch 78, said switch mounted by switch bracket 79 on brace 75. As best seen in Figure 5, the switch makes the circuit when the circular portion of shaft 73 contacts the switch arm 77. Shaft 73 extends through switch bracket 79, and a gear 80 is provided on the free end of said shaft. Gear 80 meshes with gear segment 81 on arcuatc plate 82 to cause said plate to pivot about its pivot connection 83. Secured to plate 82 is a flexible coupling 85, which extends to crank arm 61 of damper shaft 42, and is secured thereto. Sleeve 87 extends about flexible coupling and is anchored at one end by set screw 88, whereby the movement of one end of flexible coupling 85 will insure movement of the other end.

Temperature and humidity control is accomplished by means of temperature control knob 90, as best seen in Figures 1, 4 and 6. Knob 90, like knob 70, is in the shape of a ratchet wheel, having a plurality of flag fingers 91 extending therefrom. The knob is arranged on a readily accessible portion of the air conditioning unit, in this instance, at the upper right of front facade 12, as viewed in Figure 1. A single flag finger is prominently exposed at any given setting, and indicia are provided on this flag finger to indicate certain operating conditions of the unit. Temperature control knob is secured to rotate with shaft 92, extending through brace 75. The remote end of the shaft controls thermostatic switch unit 95, mounted on brace 75, as seen in Figure 4. Thermostatic switch 95 includes a fan switch 96, and a thermostat 97, as schematically illustrated in Fig 5. Fan switch 96, forming part of thermostatic switch 95 comprises a single pole, double throw switch, having switch arm 98. Thermostat 97 comprises a fiuid filled bellows 100 in communication with a bulb 101 through capillary 102. Bulb 101 is placed in the unit adjacent the portion of evaporator first contacted by the incoming air.

The bellows 100 of thermostatic unit 97 acts through a cam controlled linkage to effect operation of two switch arms 105, 1 06 controlling the compressor and circuits through the high speed and low speed coils of fan motor 36. While Figure 5 shows the thermostatic switch unit 97 diagrammatically for the purpose of its inclusion in the electrical circuit, Figures 7, 8, 9, l0 and 11 illustrate an actual construction for fullfilling the objects of this invention. The mechanical linkage includes an operating element pivotally mounted on a rod 114 connected in the sides of the casing of unit 97. One end 111 of element 110 projects through a slot in the casing and is engaged by cam 112 secured to shaft 92. Pivotally mounted on rod extending between ears on element 110 is a second element 113 having an adjustable stop 114 assembled in one end and two adjustable switch actuators 115 in the other end. In the interests of clarity, only one switch actuator is illustrated.

Thermostatic switch 95 is arranged in an electrical circuit including ventilation damper fan switch 78, fan motor 36, and the compressor motor, as best seen in Figure 5. The mode of functioning of the electrical circuit and its effect upon the operation of the herein disclosed novel unit will be made hereinafter more apparent in connection nowlunit- The above disclosed 'air conditioning unit may be most optimumly employed as a so-called room air' con ditioner for maintaining comfort conditions withina room area. To this end, the unit 10 is mounted with'one end in communication with the ambient atmosphere, and preferably arranged so that the condenser will extend outward into the ambient to dissipate the heat of the refrigeration system thereto. The evaporator 'or cooling coils 15, and the portion of the unit 10 housing same, are arranged in communication with the area to be conditioned. The unit is such as to permit a preferred arrangement where onlyfacade grill 12 extends into the conditioned area, either through a window frame, or a wall.

After installation, the unit may be employed to ventilate the conditioned area by bringing in outside air; to exhaust air from the conditioned area; to circulate the air in the conditioned area; or to cool, and/ or dehumidify the air in the conditioned area. A combination of these functions may also be provided for.

Air flow from the conditioned area through the unit 10 takes place as indicated by the directional arrows shown in Figure 1. Blower fan 29, which, as indicated, is of a squirrel cage centrifugal type, sets up an air stream through intake louvers 13, past filter 24, over cooling coils 15, into intake plenum 21. From the intake plenum 21, the air is drawn into scroll 28 through apertures 31, and is directed by fan 29 to discharge plenum 22. From discharge plenum 22, the air may be returned to the conditioned area through outlet louvers 14. The louvers 13 lie in planes parallel to each other to form a set, with the angle of said set with respect to the horizontal being different from the angle of the set of louvers 14. Since facade grill 12 may be reversed to positon either louvers 13 or 14 in an uppermost position, the amount of deflection of the air stream discharged to the conditioned area may be regulated. The air passing through plenums 21 and 22 may be treated in a variety of ways. Outside air from the ambient may be admitted to the air stream through ventilating damper 41; or alternatively a portion of the air stream may be exhausted to the ambient through exhaust damper 40. Either of the aforementioned exhaust or ventilating operations may be combined with a cooling and dehumidifying operation by passing refrigerant through cooling element or cooling of the air stream may be accomplished without either exhausting inside air, or bringing in outside air. The unit may also be employed to merely circulate air in the conditioned area.

When conditions in the conditioned area are such that it is desired to exhaust the air therefrom, as for example, when there is heavy smoking by the occupants, then with the right hand knob (as viewed in Figures 1 and 6), set in the off position, that is, with the flag finger marked Off uppermost, the left hand knob is turned in a clockwise direction from the normally Shut position to a setting with the flag fingers marked /a," 36 or EXH in an uppermost position. Each of these noted settings indicatesthat exhaust damper 40 is either .6, or fully open respectively. The opening of exhaust damper 40 is accomplished by gear 80 engaging gear segment 81 to turn plate 82 about pivot 83, thus pushing flexible coupling 85 to turn crank arm 61 to rotate damper shaft 42 in a counter-clockwise direction, as viewed in Figure 2. Rotation of damper shaft 42 causes pin 56 at the uppermost end of the shaft to rotate against lugs 55 (as seen in Figure 3), thus moving exhaust damper 40 away from exhaust port 46, against the biasing of spring 49. During this motion of damper shaft 42, lower pin 58 on shaft 42 will rotate freely without afiecting the position of ventilating damper 41. The view in Figure 2 indicates the position of the exhaust door corresponding to a 35" ventilating knob flag finger with the description of the operation of the tion' to complete a circuit through the high-speed coil of fan motor 36. The air stream set up by blower'fan 29 through intake plenum 21 and discharge plenu'm 22 will, in passing, open exhaust-port, have a portionof the air stream drawn out through the exhaust port, as a result of'the operation of condenser fan 35, which operates simultaneously with blower fan 29.

The electrical circuit indicated in Figure 5 indicates how the fan motor is actuated during the exhaust operation. Fan motor 36, which is a two-speed fan motor, is connected to'the power source through fan switch 96 and damper fan switch 78. In the exhaust setting of the controls above described, switch arm 98 of cooling fan switch 96 assumes the position illustrated by solidline in Figure 5. Under these circumstances, current flows from L through switch arm 98, through switch 78, which is closed to the Hi winding of fan motor 36, causing a circuit to be made to the high speed windings of fan motor 36. The blower fan 29 operates at high speed to direct an air stream from the conditioned area into the intake plenum and out through the exhaust port 46. Thermostat 97 is ineffective under these circumstances as will be pointed out hereafter.

When the air in the conditioned area as for example is stuffy, but not stale, or when the ambient air is at a comfortable level of temperature and humidity, and it is desired to bring this outside ambient air into the conditioned area, then temperature control knob 90, to the right as viewed in Figure l, is maintained in the Off position, and the ventilation knob 70 is turned in a counter-clockwise position from the normally Shut position to a setting with one of the flag fingers marked 6, 36, or Vent" in an uppermost position. Under these conditions, exhaust damper 40 is closed over exhaust opening 46, and ventilation damper 41 will be opened either A, or fully open, depending on the flag finger setting. As in the operation of the exhaust damper, the turning of ventilation knob 70 actuates fan switch 78, and simultaneously pulls flexible coupling to turn crank arm 42 in a clockwise direction, as yiewed in Figures 3 and 4, thereby opening ventilation damper 41. Exhaust damper 40 remains closed, since the rotation of damper shaft 42 is not transmitted to damper 40, because pin 56 does not contact lugs 55.

An important feature of the invention resides in the operation of the air conditioning unit during either the exhaust or ventilation cycle. The switch arm engaging portion of the shaft 73 is arranged so that positive actuation of the fan motor 36 is assured before either damper door is opened. This involves constructing the linkage so that a certain amount of dwell occurs in the damper actuating components to permit switch arm 77 moles switch 78. i

The electrical connection between fan switch 78 and fan motor 36 is illustrated in Figure 5, where it will be observed that this rotation of shaft 73 also causes switch arm 77 toclose a circuit from L to the Hi windings or coils of the 2-speed fan motor 36, thus initiating high speed fan operation to direct the air stream from the conditioned area through the intake and exhaust plenums drawing air from the ambient into the air stream. This is true because of the configuration of the shaft, note Figure 5.

When conditions in the conditioned area require cooling or dehumidification, and the temperature and humidity in the ambient are too high to accomplished the desired cooling by ventilation procedures, ventilation knob 70 is turned to the Shut position, closing the dampers. The control knob is turned in a clockwise direction to the Fan setting. A circuit through the low speed winding or coil of the fan motor 36 is completed as earn on shaft 92 closes microswitch 96.

The linkage consisting of elements 110 and 113 is influenced by spring 108, bellows 100 and earn 112. Switch arms 105 and 106 of the thermostatic unit 97 are maintained in the position shown in Figure when the control knob 90 is turned to the Fan" setting due primarily to the action of cam 112. To appreciate this action of cam 112 it will be noted that spring 108 urges elements 113 and 110 in a counterclockwise direction about rod 114', connected to the sides of the unit casing when the parts are in the Off position illustrated in Figure 8. This action is resisted by the engagement of earn 112 and end portion 111 of element 110. The parts are so arranged that when the control 90 is 1'0- tated to the Fan setting, the cam 112 engages lug or end portion 111 in the same manner as shown in Figure 7, note edge 119 of cam 112. Under these circumstances the length of travel of the bellows 100, in order to apply a clockwise force to the element 113 sufiicient to rotate it about 115' to actuate either switch arms 105 and 106, is at a maximum. Such a bellows expansion would normally occur at a bulb temperature substantially above those encountered in normal operation, for illustration 130 F. The switch assemblies of which arms 105 and 106 are components are conventional toggle switches of the over-center snap action type.

In the event it is desired to operate the air conditioning unit to obtain a cooling action the control knob is rotated clockwise from the Fan" setting to one of five indicated in Figure 6. These numerals tend to vary the temperatures at which the thermostat operates. Cam 112, rotating with shaft 92 presents a difierent edge portion (see Figure 9) for engagement with end portion 111 of element 110. This action causes element 110 to pivot about 114', moving rod 115 and element 113 to the right so that bellows 100 may exert a force upon element 113 that tends to move it clockwise against the action of spring 108 about pivot 115'.

Although only one switch actuating button 115 is shown, a second button similar to the one illustrated is mounted on element 113 behind the button 115 as viewed in Figures 8 and 10. The adjusting screws connecting the buttons to element 113 have different settings applied so that a sequential switch operation is obtained. In other words, when the temperature of the air entering the unit through vanes 13 approaches the value determined by the shaft setting, necessitating a need for cooling, bellows 100 expands and moves the element 113 in a clockwise direction sufiicient to permit movement of switch arm 105. Thus a circuit through-ythe compressor is completed. An additional rise in temperature of predetermined magnitude causes additional clockwise movement of the element 113 and actuation of switch arm 106. A circuit is then established through the high speed coil or winding of fan motor 36.

Upon the reduction of a desired temperature within the room served by the unit, the bellows 100 contracts and element 113 moves counterclockwise a distance sufficient to actuate arm 106 to interrupt the circuit through the high speed winding of fan motor 36 and establish once again a circuit through the low speed winding of fan motor 36. Thus, instead of the compressor cycling off to cause a rehumidification effect as the fan 29 continues air flow, the unit continues to operate and provide cooling primarily in the form of dehumidification before the compressor cycles off. The result of this reduced air flow, prior to compressor cutout, is that rehumidification effect is minimized.

The electrical circuit controlling the cooling operation is best seen in Figure 5. During the cooling operation, switch arm 98 of fan switch 96 is moved by rotation of temperature control knob 90, to the dotted line position illustrated in the drawing, thus cutting fan switch 78 out of the circuit. Under these conditions, a circuit is completed from line L through the compressor, thermostat 97, and back through line L Simultaneously, a circuit 8 is completed from line L; through the fan switch 96, through thermostat 97 to 2-speed fan motor 36, and back through line L Where, in addition to the above described cooling, it is desired to either bring in fresh air, or exhaust stale air, the left hand ventilation knob 70 may be rotated to open either the ventilation damper or the exhaust damper. If either of these dampers is opened while the cooling operation is in effect, damper fan switch 78 remains inoperative, since it is cut out of the circuit by the position of switch arm 98, as viewed in Figure 5.

It is thus seen that a novel air conditioning control system has beenprovided of a simple, inexpensive nature, having a single control knob for regulating air between the ambient and the conditioned area, and having a single knob for regulating cooling operation. A novel arrangement has been provided whereby undesirable rehumidification conventionally encountered during normal operation is minimized by reducing air circulation prior to deactivating the cooling cycle.

In summary the cooling operation is controlled by a two point thermostat. When the high point is satisfied it makes a connection to the low speed coil of the fan motor. When and if the second point is satisfied it opens the circuit through the compressor motor.

The above disclosure has been given by way of illustration and elucidation, and not by way of limitation, and it is desired to protect all embodiments of the herein disclosed inventive concept within the scope of the appended claims.

We claim:

1. In an air conditioning apparatus including a refrigeration system having a compressor and a cooling element, a two-speed fan for directing air into heat exchange relationship with the cooling element; a manually adjustable temperature responsive control regulating the operation of the fan and the compressor to shut oi the compressor, thus deactivating the refrigeration system when the temperature in the conditioned area reaches a given level, said control causing the fan to operate at high speed during normal cooling, and at low speed prior to compressor shut off, whereby rehumidification effects attendant cycling of the compressor will be reduced.

2. In an air conditioning unit including a refrigeration system having a cooling portion in communication with air from the conditioned area and a condenser portion in communication with the outside air, a fan directing air through the unit, means for controlling the passage of air through the unit, and for controlling the operation of the fan and the refrigeration system, said means comprising: a partition wall extending across the unit separating the cooling portion of the refrigeration system from the condenser, said wall having an exhaust port, and a ventilation port; an exhaust damper movably mounted over said exhaust port; a ventilating damper movably mounted over said ventilation port; a damper shaft extending between said dampers and coupled thereto to rotate therewith; a gontrol linkage coupled to said damper shaft; a fan switch electrically coupled to the fan; a ventilating control knob coupled to said linkage and to said fan to permit adjustment thereof; a thermostatically actuated switch controlling the operation of said refrigeration system and said fan, said thermostatically actuated switch deactivating said fan switch upon actuation of the thermostatically actuated switch; and a damper control knob connected to said thermostatically actuated switch to control the op eration thereof, whereby said unit may be manually controlled to provide ventilation, exhaust, and cooling of the air in the conditioned area.

3. In an air conditioning unit having electrically driven blower and compressor means, a plurality of dampers mounted on a single damper shaft for controlling air flow and a switch for controlling said electrically driven means, means for operating said dampers and said switch comprising a rotatable control member, a rotatable shaft operating said switch, a gear on said shaft meshing with a gear coupled to said damper shaft, whereby upon rotation of said control member said dampers and said switch are substantially simultaneously operated.

4. A room air conditioner comprising a compartment having a cooling element therein, means for supplying a cooling medium to the cooling element comprising a compressor, a motor operated fan for circulating room air through the compartment and cooling element therein, an opening to the compartment at the inlet side of the fan and communicating with the atmosphere outside the room, a second opening at the outlet side of the fan and communicating with the atmosphere outside the room, a damper for each opening, a single damper shaft supporting both said dampers, a switch controlling operation of the fan motor, and a single control element comprising a rotatable shaft for actuating the switch and moving the damper shaft to coordinate the opening and closing of the dampers with the operation of the fan.

5. Control means for an air conditioning system which has fan means, ventilating means admitting ventilating air through said system, exhaust means providing exhaust by said system, and cooling means for cooling air passing through said system, said control means comprising: switch means operable by a control member and adapted to energize said fan means, said ventilating means, and said exhaust means; and a thermal element powered switch means adjustable to set the operating temperature thereof, and responsive to the temperature of the room being conditioned to establish a circuit adapted to energize the, cooling means and deactivate said first named switch means.

6. Control means as in claim 5, in which said thermal element also controls fan speed.

7. In an air conditioning unit having electrically driven blower and compressor means, a plurality of dampers for controlling air flow and a switch for controlling said electrically driven means, means for operating said dampers and said switch comprising: a rotatable control member; a rotatable shaft for operating said switch; a

first gear mounted on said shaft to rotate therewith; a secmember, said dampers and said switch are substantially simultaneously operated.

8. The invention described in claim 7 wherein said control member is operative-to actuate the switch just prior to opening any of said dampers.

9. A control system for an air conditioning unit including a refrigeration system comprising a compressor, an evaporator, a condenser, fan means for supplying a first air stream over the evaporator and a second air stream over the condenser, fan motor means having a high speed winding and a low speed winding for varying the air flow over the evaporator and condenser, and damper means for admitting air to the unit or exhausting air from the unit, comprising an electrical circuit for supplying electrical energy to said compressor and selectively to said fan motor windings, damper actuating means for selectively operating said damper means for either admitting air to or exhausting air from said unit; thermostatically controlled switch means; adjustable means for regulating said thermostatically controlled switch means; first switch means operable in response to said adjustable means, second switch means operable in response to said damper actuating means, said switches being effective to complete a circuit through the high speed winding of the motor when the damper actuating means is positioned to either admit or exhaust air and the adjustable means is positioned to render the thermostatically controlled switch means inactive.

10. The invention set forth in claim 9 wherein actuation of said adjustable means interrupts the circuit through said second switch and completes a circuit through the thermostatically controlled switch for selectively'energizing the high speed and low speed windings of said fan motor in response to the load on the air conditioning unit.

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